I don't think we're talking about the same thing. I'm talking about the possibility of a purely css-based positioning that does not affect the html or the module groupings in any way.

And, yes, if I wanted to make a new base layout for the sake of just this one thing I could but I like designing on top of TR quite well and think a variable to hang the alternating css on would be a useful addition to the core itself. Part of the point of TR was to make it flexible enough to sustain a wide variety of designs.